TiO_2纳米颗粒在单晶硅表面的吸附

为了实现亚纳米级超光滑表面的加工,建立了紫外光诱导纳米颗粒胶体射流加工系统,同时研究了加工过程中纳米颗粒与工件表面间的相互作用机理。首先,对实验所用锐钛矿TiO_2纳米颗粒及单晶硅工件表面进行表征测量。然后,用第一性原理的平面波赝势计算方法研究了纳米颗粒胶体射流加工中TiO_2分子团簇在单晶硅表面化学吸附的表面构型结构及其体系能量。最后,开展了TiO_2纳米颗粒及单晶硅工件表面间的吸附实验。实验结果表明:胶体中的OH基团在TiO_2团簇表面及单晶硅表面分别发生化学吸附,在TiO_2纳米颗粒及单晶硅表面吸附过程中形成了新的Ti-O-Si键及化学吸附的H_2O分子。红外光谱实验结果显示:TiO_2纳米颗粒与单晶硅界面间存在新生成的Ti-O-Si键。这种界面间的相互作用证实了紫外光诱导纳米颗粒胶体射流抛光过程可实现材料去除的化学作用机理。

Adsorption of TiO2 nanoparticles on monocrystalline silicon surface

To efficiently create the ultra-smooth surface of brittle crystals, an ultraviolet induced nanoparticle colloid jet machining system was established and the interaction mechanism between the nanoparticles and the surface of a workpiece in the process was investigated. Firstly, the characteristics of TiO₂ nanoparticles and monocrystalline silicon surface used in the experiment were measured and investigated. Then, the plane-wave pseudopotential calculation method based on first-principles was used to study the geometrical structures and formation energies of TiO₂ molecular cluster in chemically adsorbing on hydroxyl monocrystalline silicon surface. Finally, adsorption experiments of TiO₂ nanoparticles and monocrystalline silicon surface were carried out. Calculation results show that the OH is chemically adsorbed on TiO₂ cluster and silicon surface, respectively. In the adsorption process between TiO₂ nanoparticles and silicon surface, new Ti-O-Si bonds and H₂O molecule are formed to reduce the system energy. Infrared spectral experiment results also show that there exits a new generation of Ti-O-Si bond between the interfaces of TiO₂ nanoparticles and silicon surface. The new chemical bond between the interfaces satisfies the chemical reaction mechanism in the process of ultraviolet induced nanoparticle colloid jet machining.